The World Trade Center Health Registry, the largest post-disaster exposure health registry in U.S. history, is following a diverse cohort of 71,437 directly affected people who performed 9/11-related rescue/recovery work or lived, worked or attended school in lower Manhattan on 9/11/01. The goals are to identify the long- term physical and mental health effects of the 9/11 WTC disaster; disseminate findings and recommendations to enrollees and others exposed, the public, and the scientific community; share information about 9/11-related resources and services; and inform healthcare policy and disaster response planning. Specific aims are to: (1) Maintain the Registry as a valuable public health resource; (2) Expand knowledge about the long-term physical and mental health effects of 9/11 by continuing the Registry research program; (3) Conduct community activities to respond to the physical and mental health concerns and specific healthcare needs of enrollees and others exposed to 9/11; and (4) Maintain a Treatment Referral Program to help enrollees find care for 9/11-related health problems. Aim 1 activities will sustain critical Registry infrastructure through communications and tracing activities to maintain contact with enrollees and maximize those with valid contact information; timely communications with enrollees to address concerns and keep them engaged and interested in participating in future research; outreach activities to boost response to Registry studies; and consultation with scientific, community and labor advisors. Aim 2 entails conducting priority epidemiological analyses using data from the Wave 1 (2003-04) Wave 2 (2006-08) and Wave 3 (2011-12) surveys, including analyses to assess risk factors for the development or persistence of serious respiratory and mental health conditions over time; developing and conducting a Wave 4 survey using multiple survey modes (paper, web and telephone) to ascertain the health status and 9/11-related healthcare needs of the cohort 13-14 years after 9/11; extending assessment of cancer and mortality incidence through 10 years post-9/11; and investigating potential emerging health conditions through public health surveillance and follow-up studies. The Registry will also facilitate independent and collaborative 9/11-related research by providing qualified external researchers with de- identified data and access to enrollee subgroups for recruitment. Aim 3 will be achieved by disseminating (e.g., via a web-site, annual report, e-newsletters) Registry findings and recommendations together with information on 9/11-related services and resources to enrollees, the public and policy makers; developing and providing data resources such as de-identified Registry databases and online data tools for enrollees, the public and researchers; Aim 4 will be achieved by offering healthcare referrals to enrollees with 9/11 related health conditions and symptoms based on information from the Wave 3 and 4 surveys and evaluating the program and sharing findings with the WTC Health Program.